1. Field of the Invention
The present invention relates to a structure for securing the trim cover assembly of a seat back in an automotive seat and, in particular, to such structure of a type that fixedly secures, on the back side of the seat back, two separate trim cover assemblies which are respectively used to cover the front side of the seat back and the back side of the same seat back.
2. Description of the Prior Art
Generally, to complete a seat such as a vehicle seat, a seat frame of a desired form is enclosed by a seat pad, and then the outside surface of the seat pad is covered by a trim cover assembly.
Conventionally, there have been proposed various kinds of structures for securing or covering the outer surface of a seat back of such seat with the trim cover assembly. For example, the entire peripheral surfaces are covered with the trim cover assembly in a bag manner, or, after the front surface of the seat pad is covered with the trim cover assembly, a back board comprising a hardboard or resin plate with leather or cloth adhesively applied thereto for appearance sake is attached to the back side of the seat back by means of fasteners such as tapping screws, staples or the like.
However, in the securing structure of the above-mentioned conventional seat back trim assembly, an operation of covering the seat pad with the trim cover assembly is very complicated; and, in the latter, since the head portion of the fastener is exposed, a hard image is produced. To solve this problem, for example, a seat as disclosed in Japanese Utility Model Publication No. 38131 of 1984 was proposed. In this seat, after the front surface of a seat back is covered with a trim cover assembly, a back board is engaged to two engagement pieces fixed to the two sides of a back frame by means of hook-shaped portions formed in the two side portions of the back board.
However, with this last-mentioned conventional seat, the back board is partially secured only in its two side portions to the seat back, resulting in uncertain securing strength. Also, the boundary portions between the trim cover assembly and the back board can not be brought into perfect contact to leave a clearance, which may impair the appearance of the seat. Further, the back board must be limited to a hard plate, and it is difficult to use a soft material instead of the hard plate. Accordingly, the seat provided with such back board has several drawbacks to be solved. For example, in a high-class motorcar, the seat is not suitable because it does not match the interior trim of the car.